You have probably heard that we all should eat more fish and seafood, right? What you probably haven’t heard as much about is how the source and the type of fish you eat can influence not only nutrient intake levels but also the levels of certain contaminants you consume. This is a particular concern as some fish contain antibiotics, pesticides, or other chemicals, including mercury, polychlorinated biphenyls (PCBs) and dioxins. For some individuals, for example pregnant women, this is an issue of real importance as these substances can cause harm to the developing fetus.
Despite these potential risks, it is generally accepted in the nutrition community that fish is a healthy dietary choice and regular consumption can have a positive impact on overall health. For example, the American Heart Association recommends eating fatty fish at least two times a week (AHA Omega-3 FAs), and diets such as the Mediterranean and DASH diet also promote fish consumption. Certain fish (e.g. salmon) contain high levels of omega-3 fatty acids which have anti-inflammatory properties, and may decrease risk of heart arrhythmias and blood clotting, and thus be protective against heart disease. Fish is also high in protein yet low in saturated fats.
This then leaves us in a quandary. How are we to eat more fish and other seafood, yet avoid exposing ourselves to dangerous environmental contaminants? The answer lies in the type of fish we consume, whether it was farm raised or caught in the wild and the frequency with which we consume the fish. Let’s look at species first. Contaminants are most likely to be present in older, larger predatory fish, such as shark, swordfish, king Mackerel and tilefish (Mayo Clinic Fish Info). The U.S. Food and Drug Administration (FDA) thus recommends that young children and pregnant and lactating women avoid eating these fish. It is also important to keep in mind, that not all fish and other seafood are high in omega-3 fatty acids. Some however, contain significant levels of omega-3 fatty acids and also have lower levels of environmental contaminants. These include salmon, canned light tuna, shrimp, pollock and catfish, which then are the best choice for consumers.
Two other issues to consider are the source of the fish and whether taking fish oil supplements is a good alternative. As you may or may not know, many fish such as tilapia are raised in “fish farms”. These aquaculture facilities raise large numbers of fish in relatively tight quarters. This leads to an increase in the risk for infection and other illnesses; antibiotics are thus routinely used in this setting. It is also important to consider whether the fish was imported into the U.S. from another country, as the inspection process may not be so robust. Moreover, there is some evidence that the nutrient content of wild caught fish is higher, but the price may also be higher. And lastly, there is emerging evidence in the nutritional sciences world that fish oil supplements do NOT provide the same health benefits that regular consumption of certain fish.
In summary, eating fish is good for us, but we have to be educated to realize the greatest health benefits. This general rationale also applies to many other aspects of healthy eating, such as choosing fruits and vegetables with the lowest levels of contaminating pesticides. So, learn, procure, cook and enjoy!
(written with the creative assistance of Avery Bramnik and Nicole Solomon, both University of Florida undergraduate students)